This invention relates generally to medical devices, and more particularly, to endovascular stent grafts and methods for treating branched vessels.
Stent grafts may be inserted into an anatomical vessel or duct for various purposes. For example, stent grafts are used for treatment of vasculature in the human or animal body to bypass a repair or defect in the vasculature or to maintain or restore patency in a formerly blocked or constricted passageway. For example, a stent graft may extend proximally and/or distally away from a vascular defect, including a diseased portion of an aneurysm, and engage a healthy portion of a vessel wall.
In many cases, a damaged or defective portion of the vasculature may include a branched or side vessel. More particularly, endovascular treatment of aortoiliac and internal iliac aneurysms is increasing in frequency in diverse patient populations. Fenestrated devices such as branched stent grafts having a side arm extending towards the internal iliac artery are known for treating such branched vessels. However, the anatomy of the vasculature may be unique from one patient population to the next and also among individual patients. In one example, branched stent grafts have been used to treat patients having common iliac arteries of a certain average length, such as approximately 40 mm in length or greater. However, the length of the common iliac arteries among certain patient populations, especially patients of Asian descent, may be on average shorter, down to 20 mm in length or even less. As a result, precise placement of the fenestration in the branched graft, which permits placement of an “up-and-over sheath” from the contralateral femoral artery, through the ipsilateral leg to the ipsilateral internal iliac limits treatment to patients with longer common iliac arteries in order to keep the graft bifurcation near the aortic bifurcation. Further, to align the side arm of the branched graft with the orifice of the internal iliac artery may present a challenge in patients having a shorter than average anatomy.
In addition, access to and introduction of a stent graft into a branched vessel and successful deployment of a stent graft in such vessels may often depend upon a favorable layout of the arteries. One approach that has been investigated includes accessing the target location(s) within the branched vessels by a contralateral or crossover approach. In other words, a bifurcated aortic stent graft having a longer leg that extends into one common iliac artery and a shorter contralateral leg or stump extending into the other common iliac artery may first be placed. The location of the side branch extending from the longer leg of the bifurcated graft may be adjacent to the opening of the internal iliac artery depending on the particular anatomy of the patient being treated. An additional graft or extension may then be introduced into the contralateral femoral artery, over the aortic bifurcation, and through the side branch, for placement of the graft extension in the internal iliac artery.
Accordingly, in order to treat diverse patient populations including those with shorter than average iliac arteries, it may be desirable to provide a bifurcated stent graft in which the fenestration is located more proximally in order to permit proper placement of an “up-and-over sheath” and the side branch is located more proximally in order to properly align the side branch with the opening of the branched vessel (such as the internal iliac artery), all while keeping the bifurcation between the legs of the stent graft near the aortic bifurcation. While the apparatus and methods disclosed herein are generally in relation to a stent graft and method of delivery and deployment thereof into a common iliac artery where it is necessary to extend a side branch from a main portion or body of the graft into an internal iliac artery, it is also contemplated that the systems and methods are not so limited and may relate to any other target locations within a vessel lumen in which such a graft and deployment therein is necessary or desired.